Aromatic polyesters and the process of producing the same



Patented Oct. 19, 1954 AROMATIG POLYESTERS AND THE PRO CE SS: PRODUCINGTHE SAME.

J'ames' Lincoln, London, England, assignor to British CelanesevLimited,a corporation ofGreat' Britain No Drawing; Applicationluly 1,.1952,Serial No. 296,750

Gl'iaimspriori-ty; applicatiom(Greafl Briitaim July 25, 1951 Glaims. 1'

invention relates to the production: of organic polymers and is moreparticularly con-- cerned withthe productionof high-meltingpolyestersaIt is well" known to producepol'yesters by condensati'on of adi'carhoxyli'o acid with a glycol or by self-con'clensation of ahydroxy-carboxylic acid In general the products are low melting and"hence even if of sufficientl-y high molecular weight to produce'fibresare of no value for textile-fibreproduction. However, it is well knownthat by selecting certain aromatic components forthe production ofthesepolyesters'a few poly-- esters of melting point above 200 C. can-beproduced. For example, when terep-hthalic acid isconri'ensetiiwithethylene glycol the product melts at: 255 C. However, the range ofglycols suit-- ablefor condensation withterephthalic acid toproducehigh-melting polymers is very restricted, and already withtetramethylene glycol themel't ing point of. the. product is downto 2180.. Much the same applies to more. complex aromatic dicarboxylic acidssuch as 14"-clicarhoxy-diphenyl, 4.4; -(liearboxy-diphenylrmethane (i11this! case the. productxwith ethylene glycol is. suhstantially; the:only one which. melts above 2.0.0?" ear-d1 carboxy-eli-phenyl,-ethaneandsimilar oww-bifi- (.4s-' carboxyphenyl):-alhanes. The; same appliesalso; to the emu; hisMe -oarhoxyphenoxy alkanes. Again it. is knownthateither z-hydroxy methylbenzoic acid. or 4-(fi-hydroxyethoxy)-benzoicf acid; can be condensed: with. itselfto produce a.-

polymer having a; melting point. slightly above:- 201) 6.; Here again,however, the field is very restricted. and closely: analogous compounds.such as. 4-(B-hydrcxyethyl)r-henaoic' aoicl' when conclensed; withitself produces-a. polymer having; a.- melting. point. below 200 C. Thesame applies to L-(B-hydroxyethoxya -phenyl-acetic acid I. have nowfound: thatv the; introduction of a chlorine atom in the SepositioI-ivoi 4a-( fl-hydroxyethoxy-i-benzoic acid, considerably increases, themelting point of the polymer produced from the; hydroxy-carboxyli'c;acidt. Thus. whereas poly- 4 (-o hydroxyethoxy): benzoic acid melts at200. 210" 0.1. the polymer from e-(c hycl'roxyethoxy)-3-chlor-henzoicacid melts at 280-285 C. This intermediate Q-(B-hydrdxyethzixy) -3-chlor-benzoi'cacid and its; esters; for example its methyl, ethyl andphenol esters and its formyland acetyl esters, as well as. itspolymersand CO: polymers. are new compounds and form part, of the presentinvention. 7

Themeltingpointof 280-285? C isrrather high for some purposes,particularly for ease of melt.

spinning, and accordingly it. is withintthe invention. to.- iorm. a.mixture of. the: polymer with another polymer, particularlyanotherpolyester, orv to, form. a eo polymer "of, 4.- (fiehydroxyethoxyw3-ch-lor.-benzoic:-acicl with other polyester-terms ingereagentsr. Suchother: polyesteu-formingreagents. may be; otthesimple aliphatic type.such:

as hydizoxy-polymethylene carboxy-lic. acids or polymethylenedicanhoxy-lic acids-with pol-ynaethe ylene rel-5 0015;. but arepreferablyof the aromatic: type;- capabla. when condenseaaloneg. of.yielding: homopolyestersior high melting point of. the order of, 2.0.0?camera. as; setroutabove; for instance.-

tenephthal-ic. acid withethylene glycol-,Jlelfi-dicarboxy-cliphenyl withethylene glycol or the: unsubstituted;4'r-(fi-hXGlIEOXM3thOX3/J-b9nZGiG; acid...

Such. mixtures or. copolym-ers may; be. produced-J any convenientway Forexamplezthe alreadyformeot. polymer. from 4+-(.-hydroxyetho.x.y)-3-chlor-benzoie acid? may be mixed. with an. al read-yr formed. polymen...for example. from.

terephthalic acid and ethylene, glycol or from.

4.-(-,8:-hyrlroxyethoxy)-benzoic acid, and! the two polymersv quicklymelted; together to form; a mix ture,.-.or alternatively the. melting:may be con tinued until. substantially homogeneous co polymer isobtained. or the: monomeric: com,-

pounds may be mixed together initially and the whole condensed to formthe co-polyme'r.

Preferably, the amount of such admixed reagents is such that. the:melting, point of'the c0- polymer' is not less. than 230 C. and. mostadvantageously'i'sin the range of. 240j--270"v C;

The new monomer i-(fl-hydroxyethoxy) -3 chlor=benzoie acid'may beproduced.by reaction.

methylene chlorhydrin. upon. 4'-hydroXy- 3'-chlorhenzoi'c acid while theesters may be produced by esteri'fication of the free. acid, for examplewith methyl or ethyl alcohoL. or by acidylation,

e.. g .,wi'th iormic acid, acetic anhy'd'rid'e or acetyl. chloride, orother acid anhydride or hali(:le', of'

I phonic acid,. sulphamic; acizland. the like, or. all- 3 ternativelythe carboxy and hydroxy groups may be present in the form ofester-forming derivatives. For example, and this is the preferable form,the carboxy group may be present as an ester of a volatile monohydroxycompound, for example methyl alcohol, ethyl alcohol, phenol and thelike. In such a process of ester-interchange it is again preferable tohave a catalyst present, for example magnesium, sodium or sodium andmagnesium or lithium. Again the hydroxy groups may be present in theform of simple esters of acids which are readily volatile under thepolyesterification conditions. Thus the hydroxy groups may be present inthe form of formates or acetates.

Where in a reaction between a dicarboxylic acid and a glycol the glycolis volatile under the re-' action conditions, it is preferably used in alarge excess and the excess allowed to evaporate. Generally theesterification is carried out at relatively high temperatures in'themelt or in solution in an inert solvent. The temperatures of the orderof 200-250 may be used, especially in the early stages, and in the laterstages still higher temperatures, for example 250-300 C. In these laterstages it is desirable to carry out the reaction under low pressure, forexample a pressure of the order of 2 mms. of mercury or less, in orderto remove the volatile by-product, which may be a volatile mono-hydroxycompound such as methanol, ethanol or phenol, or a volatile glycol suchas ethylene glycol. The esterification is preferably continued until aproduct having fibre-forming properties is produced. For this purposethe reagents, if substantially non-volatile under the reactionconditions, should be employed in such proportions that there aresubstantially equal numbers of hydroxy and carboxy groups or theirequivalents in the reaction mixture. Where one of the reagents isvolatile and is allowed to evaporate during the reaction, that reagentshould be employed in excess.

The following examples illustrate the production of the intermediate andof the polymers according to the invention, all parts being by weight.

The reaction temperatures in the various polymerisations are oil bathtemperatures.

Example 1.- -Preparation of the 3-chlo'ro acid Example 2.Prepamtion ofthe ethyl ester of the acid 26 parts of the acid made according toExample 1 were refluxed with 300 parts of dry ethanol and 9.2 parts ofconcentrated sulphuric acid for 7 /2 hours. The solution was neutralisedwith sodium bicarbonate and filtered. Most of the ethanol was thendistilled off from a water-bath and the residue poured into water. Anoil at first appeared which subsequently solidified. At this stage ithad a melting point of 6773 C. It was recrystallised from a mixture ofpetrol ether 4 and. benzene (5 vols. petrol ether, 2 vols. benzene) togive an ester having a melting point of C.

Example 3.--Preparation of the homo-polymer The ester produced accordingto Example 2 was mixed with a small quantity of magnesium ribbon and ofsodium methylate dissolved in methanol and the mixture gradually heatedup to 200 C. After 15 minutes at this temperature the polymer had setsolid. It was re-melted at a temperature of 320 C. and heatingcontinued. The final product had a melting point of 280- 285 C.

Example 4.Pr0cluct2on of co-polymer with terep-hthalate and glycol 18parts of the ester obtained according to Example 2, 4 parts of dimethylterephthalate and 1.9 parts of ethylene glycol were mixed with a smallquantity of magnesium ribbon and of sodium methylate in methanol and themixture was refluxed under a water-cooled condenser for 45 minutes at C.The condenser water was then run out and the temperature graduallyraised to C. After 30 minutes the condenser was removed and heatingcontinued at the same temperature for 30 minutes and the temperaturethen raised to 260 C. during 45 minutes. This temperature was maintainedfor another hour and then raised to 280 C. for 4 hours. At this stagethe product melted at 232-236 C. and gave brittle fibres. Heating wascontinued for a further 5 hours at 280 C. under an absolute pressure of1 mm. of mercury. The'melting point of the product remained the same andthe polymer at the end of this further period of heating gave fibresfrom the melt having good cold-drawing properties.

Example 5.Production of co-polymer with hydromyethory-benzoic acid 2parts of the ester obtained according to Example 2 were mixed with 1part of methyl-4- (fi-hydroxyethoxy)-benzoate and a small quantity ofmagnesium ribbon and of sodium methylate dissolved in methanol, and themixture was heated slowly without a condenser while the solventdistilled off. On continued heating after 2 hours the temperature hadreached 260 C. and the melt became more viscous. After a further 20minutes the product solidified to a creamy solid. The temperature wasthen raised to 280 C. and thence to 290 C. After 4 hours of this furtherheating the pressure was reduced to an absolute pressure of 1 mm. ofmercury and these conditions maintained for '75 minutes. The product wasa hard crystalline polymer having a melting point of 255260 C. and itgave fibres which could be cold drawn.

Having described my invention, what I desire to secure by Letters Patentis:

l. 4-(fi-hydroxyethoxy) -3-chlorbenzoic acid.

2. An ester of e-(fi-hydroxyethoxy) -3-chlorbenzoic acid with a compoundcontaining an CH group.

3. An ester of 4-(fi-hydroxyethoxy)-3-chlorbenzoic acid with a compoundcontaining a single OH group volatile at 300 C.

4. A substance selected from the group con sisting of the methyl, ethyl,formyl and acetyl esters of 4-(j3-hydroxyethoxy)3-chlorbenzoic acid.

5. Poly-l-(B-hydroxyethoxy) -3-chlor-benzoic acid.

6. A polymer whose structural units consist predominantly of 7. Apolyester of 4-(5-hydroxyethoxy) -8-chlorbenzoic acid.

8. A polyester of a major proportion of 4-(5- hydroxyethoxy)-3-chlorbenzoic acid and a minor proportion of another hydroxycarboxylic acid.

9. A polyester of a glycol, a dicarboxylic acid and a major proportionof 4-(p-hydroxyethoxy) 3-chlorbenzoic acid.

10. A polyester of 4-(p-hydroxyethoxy) -3- chlorbenzoic acid and anotheraromatic hydroxy carboxylic acid, said polyester having a melting pointof at least 230 C.

11. A polyester as set forth in claim 10 in which said other hydroxyacidis 4-(B-hydroxyethoxybenzoic acid, said polyester having a melting pointof 240 to 270 C.

12. A polyester of 4-(p-hydroxyethoxy)-3- 13. A polyester as set forthin claim 12 in which said glycol is a polymethylene glycol and saidaromatic dicarboxylic acid is terephthalic acid.

14. A polyester as set forth in claim 13 in which said glycol isethylene glycol, said polyester haying a melting point of 240 to 270 C.

15. Process for the production of polymers which comprises heating apolyester-forming composition comprising predominantly a substanceselected from the group consisting of i-(p-hydroxyethoxy)-3-chlorbenzoicacid and esters thereof with monohydroxy compounds volatile at 300 C. toproduce a polyester.

UNITED STATES PATENTS Name Date Cook et al May 24, 1949 Number

